Proton Transfer Rates in Ionized Hydrogen Chloride–Water Clusters: A Direct Ab Initio Molecular Dynamics Study

2017 ◽  
Vol 121 (28) ◽  
pp. 5237-5244 ◽  
Author(s):  
Hiroto Tachikawa
Keyword(s):  
Molecular Dynamics ◽  
Proton Transfer ◽  
Ab Initio ◽  
Hydrogen Chloride ◽  
Water Clusters ◽  
Ab Initio Molecular Dynamics ◽  
Transfer Rates ◽  
Chloride Water

Effect of anion reorientation on proton mobility in the solid acids family CsHyXO4 (X = S, P, Se, y = 1, 2) from ab initio molecular dynamics simulations

2020 ◽  
Vol 22 (19) ◽  
pp. 10738-10752 ◽  
Author(s):  
Christian Dreßler ◽  
Daniel Sebastiani
Keyword(s):  
Molecular Dynamics ◽  
High Temperature ◽  
Proton Transfer ◽  
Ab Initio ◽  
Solid Acids ◽  
Ab Initio Molecular Dynamics ◽  
Proton Mobility ◽  
Transfer Rates ◽  
High Proton ◽  
Dynamics Simulations

The high temperature phases of the solid acids CsHSeO4, CsHSO4 and CsH2PO4 show extraordinary high proton conductivities, which are enabled by the interplay of high proton transfer rates and frequent anion reorientation.

Electrons in Cold Water Clusters: An ab Initio Molecular Dynamics Study of Localization and Metastable States

2010 ◽  
Vol 114 (48) ◽  
pp. 20489-20495 ◽  
Author(s):  
Ondrej Marsalek ◽  
Frank Uhlig ◽  
Pavel Jungwirth
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Cold Water ◽  
Water Clusters ◽  
Metastable States ◽  
Ab Initio Molecular Dynamics

scholarly journals Resolving the HONO formation mechanism in the ionosphere via ab initio molecular dynamic simulations

2016 ◽  
Vol 113 (17) ◽  
pp. 4629-4633 ◽  
Author(s):  
Rongxing He ◽  
Lei Li ◽  
Jie Zhong ◽  
Chongqin Zhu ◽  
Joseph S. Francisco ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Nitrous Acid ◽  
Water Clusters ◽  
Ab Initio Molecular Dynamics ◽  
Molecular Dynamic Simulations ◽  
Global Minima ◽  
Dynamic Simulations ◽  
Transition State Search ◽  
A Chain

Solar emission produces copious nitrosonium ions (NO+) in the D layer of the ionosphere, 60 to 90 km above the Earth’s surface. NO+ is believed to transfer its charge to water clusters in that region, leading to the formation of gaseous nitrous acid (HONO) and protonated water cluster. The dynamics of this reaction at the ionospheric temperature (200–220 K) and the associated mechanistic details are largely unknown. Using ab initio molecular dynamics (AIMD) simulations and transition-state search, key structures of the water hydrates—tetrahydrate NO+(H2O)4 and pentahydrate NO+(H2O)5—are identified and shown to be responsible for HONO formation in the ionosphere. The critical tetrahydrate NO+(H2O)4 exhibits a chain-like structure through which all of the lowest-energy isomers must go. However, most lowest-energy isomers of pentahydrate NO+(H2O)5 can be converted to the HONO-containing product, encountering very low barriers, via a chain-like or a three-armed, star-like structure. Although these structures are not the global minima, at 220 K, most lowest-energy NO+(H2O)4 and NO+(H2O)5 isomers tend to channel through these highly populated isomers toward HONO formation.

scholarly journals Proton Transfer from a Photoacid to Water: First Principles Simulations and Fast Fluorescence Spectroscopy

2021 ◽  
Author(s):  
Alice R. Walker ◽  
Boning Wu ◽  
Jan Meisner ◽  
Michael D. Fayer ◽  
Todd J. Martinez
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Fluorescence Spectroscopy ◽  
Proton Transfer ◽  
Ab Initio ◽  
Time Constant ◽  
Emission Wavelength ◽  
Ab Initio Molecular Dynamics ◽  
Long Distance ◽  
Hydrogen Bonded

Proton transfer reactions are ubiquitous in chemistry, especially in aqueous solutions. We investigate photo-induced proton transfer between the photoacid 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) and water using fast fluorescence spectroscopy and ab initio molecular dynamics simulations. Photo-excitation causes rapid proton release from the HPTS hydroxyl. Previous experiments on HPTS/water described the progress from photoexcitation to proton diffusion using kinetic equations with two time constants. The shortest time constant has been interpreted as protonated and photoexcited HPTS evolving into an “associated” state, where the proton is “shared” between the HPTS hydroxyl and an originally hydrogen bonded water. The longer time constant has been interpreted as indicating evolution to a “solvent separated” state where the shared proton undergoes long distance diffusion. In this work, we refine the previous experimental results using very pure HPTS. We then use excited state ab initio molecular dynamics to elucidate the detailed molecular mechanism of aqueous excited state proton transfer in HPTS. We find that the initial excitation results in rapid rearrangement of water, forming a strong hydrogen bonded network (a “water wire”) around HPTS. HPTS then deprotonates in ≤3 ps, resulting in a proton that migrates back and forth along the wire before localizing on a single water molecule. We find a near linear relationship between emission wavelength and proton-HPTS distance over the simulated time scale, suggesting that emission wavelength can be used as a ruler for proton distance. Our simulations reveal that the “associated” state corresponds to a water wire with a mobile proton and that the diffusion of the proton away from this water wire (to a generalized “solvent-separated” state) corresponds to the longest experimental time constant.

Surface solvation of halogen anions in water clusters: An ab initio molecular dynamics study of the Cl−(H2O)6 complex

2001 ◽  
Vol 114 (16) ◽  
pp. 7036-7044 ◽  
Author(s):  
Douglas J. Tobias ◽  
Pavel Jungwirth ◽  
Michele Parrinello
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Water Clusters ◽  
Ab Initio Molecular Dynamics

Solid-state proton conduction: An ab initio molecular dynamics investigation of ammonium perchlorate doped with neutral ammonia

2004 ◽  
Vol 76 (1) ◽  
pp. 49-61 ◽  
Author(s):  
L. Rosso ◽  
M. E. Tuckerman
Keyword(s):  
Molecular Dynamics ◽  
Proton Transfer ◽  
Ab Initio ◽  
Ammonium Perchlorate ◽  
Direct Evidence ◽  
Orthorhombic Phase ◽  
Ab Initio Molecular Dynamics ◽  
Cubic Phase ◽  
Diffusion Constants ◽  
Lower Frequency Region

The charge-transport mechanism in solid ammonium perchlorate crystal exposed to an ammonia-rich environment is studied using ab initio molecular dynamics. Ammonium perchlorate is an ionic crystal composed of NH4+ and ClO4- ; units that possesses an orthorhombic phase at T < 513 K and a cubic phase at T > 513 K. Exposure to an ammonia-rich atmosphere allows ammonia molecules to be absorbed into the crystal at interstitial sites. It has been proposed that these neutral ammonias can form short-lived N2H7+ complexes with the NH4+ ions allowing proton transfer between them, thereby enhancing the conductivity considerably. To date, however, there has been no direct evidence of this proposed mechanism. In this paper, ab initio molecular dynamics techniques are employed to explore this mechanism. By comparing computed infrared spectra of the pure and ammonia-doped crystals, we observe a significant broadening of the NH stretch peak into a lower frequency region, indicating through an experimentally verifiable observable, the formation of hydrogen bonds between NH3 and NH4+ units. This suggestion is confirmed by direct observation of N2H7+ complexes from the trajectory. Comparison of the diffusion constants of NH4+ in the pure and doped crystals yields a ratio that is comparable to the experimentally measured conductivity ratio and clearly shows an enhanced positive charge mobility. Finally, compelling evidence suggesting the possibility of an ammonia umbrella inversion following proton transfer from NH4+ and NH3 is obtained.

scholarly journals Ab initio molecular dynamics study of glycine intramolecular proton transfer in water

2005 ◽  
Vol 122 (18) ◽  
pp. 184506 ◽  
Author(s):  
Kevin Leung ◽  
Susan B. Rempe
Keyword(s):  
Molecular Dynamics ◽  
Proton Transfer ◽  
Ab Initio ◽  
Intramolecular Proton Transfer ◽  
Ab Initio Molecular Dynamics

scholarly journals Ab initio molecular dynamics simulations of aluminum ion solvation in water clusters

2000 ◽  
Vol 322 (6) ◽  
pp. 447-453 ◽  
Author(s):  
M.I. Lubin ◽  
E.J. Bylaska ◽  
J.H. Weare
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Water Clusters ◽  
Ion Solvation ◽  
Ab Initio Molecular Dynamics ◽  
Aluminum Ion ◽  
Dynamics Simulations
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